Conditions InDepth: Pneumonia

Pneumonia is a serious infection of the lungs that causes the air sacs in the lungs to fill with pus and other liquid. The infection may be caused by bacteria, viruses, fungi, and mycoplasma.
In general, pneumonia is divided into 2 types: community-acquired, or hospital- or nursing home-acquired.

You may get pneumonia through a simple encounter with an organism that you breathe into your lungs. Whether or not illness occurs depends several factors, including the contagiousness of the organism, the number of organisms that are inhaled, and the ability of the immune system to fight infections.

In the US, pneumonia is a very common illness, especially among people who are elderly.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.